Electrofluid is also known as electrowetting. At current, the electrofluidic display (EFD) technology has been widely used, and it provides an electrofluid-based display unit.
For example, an electrofluidic device described in International Patent Application WO 2003/071346 comprises two support plates. A walls pattern (i.e., pixel wall) is arranged on one of the support plates, and the walls pattern defines an image element of the display device. An area between the walls of the image element (also known as pixel) is known as a display area, and a display effect is generated on the display area. The walls of the image element is made of a hydrophilic material. A wide range of the area of the support plate in the display area has to be hydrophobic for proper handling of the image element. During manufacturing, the area where the image element is located in the support plate is covered by a hydrophobic layer. The walls are manufactured by depositing a layer of walls material on the hydrophobic layer and patterning the layer of walls material using (for example) a photoetching method.
Since the walls material layer is hydrophilic, an adhesive force between the walls material layer and the hydrophobic layer is relatively weak, resulting in easy release of the walls material layer from the hydrophobic layer. It is known to reduce the hydrophobicity of the hydrophobic layer before applying the walls material layer, for example, by reactive ion etching. After forming the walls, the hydrophobic layer is heated to restore its hydrophobicity. However, during the plasma etching or heat treatment, the hydrophobic layer will inevitably be damaged and the hydrophobic and insulating properties will be affected. This will cause the ink (oil) incompletely return problem when the voltage is turned off. Therefore, the quality of the display device manufactured by the method is unsatisfactory.
For this reason, some improvements have also been made. For example, a solution, proposed in the application with Application No. CN201410159289.1, is that a hydrophobic layer material is arranged on a support plate with a hydrophilic layer material, and a hydrophobic surface can be protected from damage by means of a method of adding a protective layer in a groove in the hydrophobic surface and then etching, solving the quality problem caused by the damage of the surface of the hydrophobic layer. However, there is a problem with this method. After the hydrophobic material being etched into a grid-like pattern, a short-circuit problem will be caused by the water on the hydrophobic insulated layer (or ionic liquid or a salt solution such as an aqueous solution of sodium chloride) contacting a lower electrode after switching on and off many times due to a gap between the hydrophobic layer and the walls material while bonding, thereby affecting the reliability of the device.